His patronage of the weather arose when monks tried to translate his body from an outdoor grave to a golden shrine in the Cathedral in 871. Swithun apparently did not approve as it started raining for 40 days. The weather on the festival of his translation indicates, according to an old rhyme, the weather for the next forty days:

Saint Swithun’s day, if thou dost rain,
For forty days it will remain;
Saint Swithun’s day, if thou be fair,
For forty days ’twill rain nae mair.